Do I really have to do work today?

I spend 80-90% of my days doing nothing, so when someone asks me to do something, it's almost as if I'm annoyed. I've spent the past 6 hours staring at my computer screen and trying to find ways to occupy my time, and NOW all of a sudden you want something?

I try to explain to my family and friends what it's like coming to work every day knowing that you won't be doing (much of) anything. The generic reply is, "You're getting paid to do nothing!" But inside, I just feel useless and unproductive in my career. For the first few weeks, I can understand ones perception of how amazing my situation is. But months into it? The few times I'm asked to do something, it's unchallenging and short-lived. We spend so much time at work and away from our friends and family that it doesn't seem right to be doing nothing while I'm at the office.